Pivoted jaw wrench



July 10, 1951 B. P. KUNZ PIVOTED JAW WRENCH Filed Oct. 22, 1947 IN V EN TOR. fiernaro K002 ATTORNEY Patented July 10, 1951 UNITED STATES PATENT OFFICE PIVOTED JAW WRENCH Bernard P. Kunz, Aurora, 0010.

Application October 22, 1947, Serial N 0. 781,379

1 Claim. 1 V This invention relates to wrenches and more particularly to a wrench having quickly separable jaws for gripping and turning different size members such as pipe, bolts, nuts, etc.

One of the objects of the invention is to produce an improved wrench of the swingingjaw type which can be quickly applied to different size members and operate without slipping on all of said members.

Yet another object is to produce a swinging jaw type of wrench in which the various jaw faces are so formed and have such relation to each other and to the pivotal axis of the swinging jaw that an improved and more efficient gripping action will be accomplished.

A further object is to so construct the jaw faces of a swinging jaw type of wrench that an improved, widely spaced three-point engagement of the member to be gripped will be present and all engaged points will have pressure engagement with the member which increases with increased manual force applied to the wrench.

A still further object is to embody in a wrench of the type referred to an improved curved jaw face for cooperation with the jaw faces of a swinging jaw.

A more specific object is to construct the swinging jaw of a wrench so as to have right angle jaw faces and to associate with such jaw a cooperating jaw having such a special face curvature and being so related to the pivotal axis of the swinging jaw that all various size members selected to be gripped will have a force acting thereon which will be in such a direction as to cause the member to have improved pressure engagement with both of the right angular related jaw faces of the swinging jaw.

Other objects of the invention will become apparent from the following description taken in connection with the accompanying drawings showing a wrench embodying said invention.

In the drawings:

Figure 1 is a side view of a wrench;

Figure 2 is a top view of the wrench; and

Figure 3 is an outline view of the wrench, together with dashed line views of various positions of the swinging jaw which are assumed when the wrench is gripping various sizes of round members, said vie-w also showing the manner in which the curvature of the jaw face on the handle is. determined and also other structural relationships.

Referring to the drawings in-detail, the improved wrench disclosed by the various figures comprises a handle member I and a swinging or pivoted jaw member 2. The handle member at one end has a hand gripping portion 3 and at its other end a laterally extending jaw portion 4. The swinging jaw member 2 is of general L-shaped form having its longest leg portion enlarged somewhat and pivotally mounted to the jaw portion end of the handle member I by means of a pivot pin 5. The free end of the longest leg portion is reduced in thickness and is arranged to be received in a handle slot 6. The pivot pin has its ends bearing in the handle member on opposite sides of the slot with the central part of the pin extending through the reduced portion of the jaw member 2. A spring 'l is arranged to have one end connected to a pin 8 carried by the jaw member below its pivot and its other end connected to a pin 9 extending across the rear end of the slot 6 which, it is to be noted, extends a considerable distance rearwardly from the pivot pin 5.

The longer leg portion of the swinging jaw member is provided with a jaw face In and the other leg portion of said swinging jaw member is provided with .a jaw face H. These two jaw faces are arranged to be preferably at right angles to each other, although this relationship may be slightly varied within limits. The degree relationship is the most desirable, but it is possible for the wrench to operate in a reasonably efiicient manner if the jaw faces have either a slightly greater or less angular relationship than 90 degrees. The jaw face I0 is provided with teeth l2 and the jaw face I I is provided with teeth 13 so as to provide a better gripping surface with any member to be operated upon by the wrench.

The laterally extending jaw portion 4- at the end of the handle member I of the wrench is provided with an outwardly curved jaw face t4 and this face has teeth l5 so that it may better grip the surface of the member which is to be operated upon by the wrench. The curved jaw face M has a greater or sharper curvature at its outer end portion (the portion remote from the pivot 5) then it has closer to or adjacent the pivot 5. The curvature of the face M can be obtained by a plurality of arcs, or it is possible to obtain the curvature by a curve that follows a mathematical formula. In the particular wrench disclosed, as is best illustrated in Figure 3., the outwardly curved face i4 is formed from two arcs A and A. Since these two arcs: are arranged to form a continuous curved surface, the. centers of the arcs will lie on a common radial line which is indicated as L on Figure 3.

The are A, which has a greater radius of ourvature than the are A, is over the inner end portion of the curved face N, that is, the portion of the curved face which is closest to the axis of the pivot pin 5. The radius of this imier are A is indicated in Figure 3 by the letter R and the radius of the outer curved are A is indicated by the letter R. These two radii, in order to produce the proper curvature of the curved face l4 and provide for the wrench having its greatest efficiency, have a definite relationship with respect to each other. The radius R should be at least greater than twice the radius R and in the particular wrench shown in the drawings as an example of a wrench embodying the invention, the relationship between the radii R and R is 3 to l.

The relationship of the two right angle related jaw faces I and II on the pivoted jaw member 2 to the curved jaw face I4, and also the pivot of said pivoted jaw member, is another important feature of the invention embodied in the wrench in order that the wrench may operate in an eflicient manner. For any particular size wrench, that is, a wrench designed to operate efficiently on members within certain selected limits, the shorter radius R for the arc A should be somewhere within to 50 percent of the distance from the axis of the pivot 5 to the jaw face ll. Thus if the wrench is designed for operation upon a two inch pipe as a maximum-member, then the distance between the pivotal axis 5 and the jaw face Ii will be selected so that a two inch diameter pipe can fit between said jaw face H and the curved jaw face l4 when the pivoted jaw member is fully opened. With this distance determined, then the radius R will be selected somewhere between 40 and 50 percent of the distance between the pivotal axis of the pin 5 and the jaw face H. The jaw face ill on the pivoted jaw member must also lie in a plane which will have a definite relationship to the pivotal axis 5. On Figure 3 the plane in which the jaw face H lies is indicated by the letter P. In designing the wrench, this plane P must not be closer to the pivotal axis 5 than the distance between the pivotal axis and the inner end of the curved jaw face 14, that is, the inner end of are A. In Figure 3 the shortest distance between the plane P and the axis of pivot pin 5 is indicated as S and the distance from the pivotal axis to the nearest end of the curved jaw face I4 is indicated as N. To have the wrench operate with maximum efliciency, S should never be less than N.

The reason that the curved jaw face [4 must be outwardly curved and have a smaller radius of curvature at its outer end than at portions closer to the pivot 5 can be best understood by reference to Figure '3. In this figure there is shown the various positions of the jaws when operating upon various sized round members such as pipes. Three different sized round members are shown and indicated by M, M and M For all these sizes of round members, the wrench will always act thereon in substantially the same manner and this is accomplished by the particular curvature of the curved jaw face l4 and its relation to the pivoted jaw member having the right angle jaw faces, together with the relationship of the various faces to the pivotal axis of the pivoted jaw member. It will be noted that for any size round member, the curved jaw face [4 will engage said member at a point X which is inwardly of the point where the line bisecting the right angle between the faces H and i2 intersects the surface of the particular round member which is remote from the jaw faces l0 and l I. This point is indicated at Z on Figure 3. With the engagement of the curved jaw face at the point X inwardly of the point Z, the circular member will always be forced into pressure engagement, not only with the jaw face H, but also with the jaw face 10 and the pressures will always increase with any increase in a force operating on the handle member I to either turn or hold the circular member. To have proper operation of the wrench, the angular distance between the point X and the point Z should never be less than '7 degrees. Thus the illustrated smallest member M which can be received by the wrench, will be acted upon in the same manner as the largest member M which can be received by the wrench. Consequently, the wrench will operate very efficiently upon all sizes of members for which the wrench is designed.

In order further to have an efficiently operat ing wrench and particularly one which can have quick gripping action without slipping when it is to be operated, the longitudinal axis of the handle member 1 should bear a particular relationship to the axis of the pivot pin 5. In the wrench shown the longitudinal aXis of the handle member I passes below the axis of the pin 5. When the handle is gripped and a force is applied to the handle, it will generally act in substantially the direction indicated by F in Figure 3, due to the position of the operators arm when he operates the wrench. With the force F having the direction indicated, it is to be noted that there will be a resultant force acting to turn the handle member about the axis of the pin 5 and also there will be another and smaller resultant force acting in the longitudinal direction of th handle member and tending to push the curved jaw face l l into engagement with the member to be operated upon. Consequently, the curved jaw face M will be held against the member operated upon and gripping action will occur immediately and there will be less tendency of the wrench to slip around the member before gripping action takes place. Other relationships of the handle to the axis of pin 5 can be had to obtain the same result. The principle feature is to have a resultant force acting below pin 5 and in a direction to push jaw face l5 into the member to be acted upon.

It is believed to be obvious how the wrench is operated. All that need be done is open up the pivoted jaw member 2 a suiiicient distance so that the member to be operated upon can be received and engaged by all the jaw faces. The opening of the pivoted jaw member can be facilitated by providing the rear end of the pivoted jaw member with a protuberance 15 which can be conveniently pushed upon by a thumb of the operators hand. The action of the spring I, when the wrench is placed upon the member to be operated, will be such as to cause all the jaw faces to have some pressure engagement with the surface of the member. When force is applied to the handle member of the wrench the member to be operated upon will then immediately be gripped by the various jaw faces, this gripping being facilitated by the teeth. The greater the force applied to the handle member of the wrench, the greater will be the gripping action. All the jaw faces will have a gripping action with the member to be operated upon. The greatest gripping action will be by the curved jaw face l4 and the jaw face H. Due to the construction of the wrench, however, there will also be considerable gripping action by the jaw face 12. The pressure engagement between each jaw face and the member operated upon will increase along with any increase in force applied to the handle member of the wrench. The points at which any member is gripped will never be closer than 90 degrees. This insured spacing of the three gripping points will result in efiicient operation. The wrench is removed from the member being operated on by merely reversing the force acting upon the handle member as when such force is applied the jaw will open.

Being aware of the possibility of modifications in the particular wrench shown by way of example as embodying the invention and without departing from the fundamental principles of theinvention, it is not intended that the scope be limited in any manner except in accordance with the appended claim.

What is claimed is:

In a wrench of the class described, a handle member having an integral jaw portion at one end, said jaw portion having a curved jaw face formed of two distinct arcs of substantial length, the centers of which lie on a common radial line, and a jaw member having an inwardly directed extension pivoted to the jaw portion of the handle member in spaced relation to said curved face and formed to provide two right angle related faces, the centers of the two arcs of the curved jaw face being on that side of said curved jaw face away from the faces of the swinging jaw and the are nearest the pivoted axis of the pivoted jaw having a radius at least twice as great as that of the other are of said curved face and the length of the smaller radius being between forty and fifty percent of 6 the distance from the pivotal axis to the most remote face of the right angle faces, said pivoted jaw member having its pivot axis outwardly spaced from the longitudinal axis of the handle, and spaced from a plane containing the adjacent right angularly related face by a distance at least as great as the distance between said pivot axis and the adjacent portion of said curved jaw, whereby said pivot axis is so related to the arcs of the curved jaw face that when various size circular members are positioned between the jaws of the wrench each circular member will be engaged by the curved jaw face at a point more than degrees from either point engaged by faces of the pivoted jaw and inwardly by at least 7 degrees from a point where the line bisecting the right angle of the pivoted jaw faces intersects the surface of the circular member remote from said pivoted jaw faces.

BERNARD P. KUNZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 434,847 Taylor Aug. 19, 1890 506,070 Plante Oct. 3, 1893 609,545 Hollingsworth Aug. 23, 1898 800,850 Irland Oct. 3, 1905 1,281,020 Johnson Oct. 8, 1918 1,532,803 Fowler Apr. 7, 1925 FOREIGN PATENTS Number Country Date 2,524 Great Britain Oct. 15, 1863 20,392 Great Britain Sept. 18, 1902 9,137 Great Britain Apr. 18, 1913 

